Chemistry

Paul Flower, Klaus Theopold, Richard Langley

Chapter 20

Organic Chemistry - all with Video Answers

Educators

Chapter Questions

Problem 1

Write the chemical formula and Lewis structure of the following, each of which contains five carbon atoms:
(a) an alkane
(b) an alkene
(c) an alkyne

Aadit S.

Aadit S.

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Problem 2

What is the difference between the hybridization of carbon atoms' valence orbitals in saturated and unsaturated hydrocarbons?

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Problem 3

On a microscopic level, how does the reaction of bromine with a saturated hydrocarbon differ from its reaction with an unsaturated hydrocarbon? How are they similar?

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Problem 4

On a microscopic level, how does the reaction of bromine with an alkene differ from its reaction with an alkyne? How are they similar?

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Problem 5

Explain why unbranched alkenes can form geometric isomers while unbranched alkanes cannot. Does this explanation involve the macroscopic domain or the microscopic domain?

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Problem 6

Explain why these two molecules are not isomers:

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Problem 7

Explain why these two molecules are not isomers:

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Problem 8

How does the carbon-atom hybridization change when polyethylene is prepared from ethylene?

Aadit S.

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Problem 9

Write the Lewis structure and molecular formula for each of the following hydrocarbons:
(a) hexane
(b) 3 -methylpentane
(c) cis-3-hexene
(d) 4 -methyl-1-pentene
(e) 3-hexyne
(f) 4 -methyl-2-pentyne

Aadit S.

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Problem 10

Write the chemical formula, condensed formula, and Lewis structure for each of the following hydrocarbons:
(a) heptane
(b) 3 -methylhexane
(c) trans-3-heptene
(d) 4 -methyl-1-hexene
(e) 2 -heptyne
(f) 3,4 -dimethyl-1-pentyne

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Problem 11

Give the complete IUPAC name for each of the following compounds:
(a) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CBr}_{2} \mathrm{CH}_{3}$
(b) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}$
(c)
(d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}$
(e)
(f)
(g) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{CH}_{2}$

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Problem 12

Give the complete IUPAC name for each of the following compounds:
(a) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHF}$
(b) $\mathrm{CH}_{3} \mathrm{CHClCHClCH}_{3}$
(c)
(d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CHCH}_{3}$
(e)
(f) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}_{2} \mathrm{C} \equiv \mathrm{CH}$

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Problem 13

Butane is used as a fuel in disposable lighters. Write the Lewis structure for each isomer of butane.

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Problem 14

Write Lewis structures and name the five structural isomers of hexane.

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Problem 15

Write Lewis structures for the cis-trans isomers of $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCl}$.

Nicholas S.

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Problem 16

Write structures for the three isomers of the aromatic hydrocarbon xylene, $\mathrm{C}_{6} \mathrm{H}_{4}\left(\mathrm{CH}_{3}\right)_{2}$.

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Problem 17

Isooctane is the common name of the isomer of $\mathrm{C}_{8} \mathrm{H}_{18}$ used as the standard of 100 for the gasoline octane rating:
(a) What is the IUPAC name for the compound?
(b) Name the other isomers that contain a five-carbon chain with three methyl substituents.

Aadit S.

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Problem 18

Write Lewis structures and IUPAC names for the alkyne isomers of $\mathrm{C}_{4} \mathrm{H}_{6}$.

Aadit S.

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Problem 19

Write Lewis structures and IUPAC names for all isomers of $\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Cl}$.

Nicholas S.

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Problem 20

Name and write the structures of all isomers of the propyl and butyl alkyl groups.

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Problem 21

Write the structures for all the isomers of the $-\mathrm{C}_{5} \mathrm{H}_{11}$ alkyl group.

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Problem 22

Write Lewis structures and describe the molecular geometry at each carbon atom in the following compounds:
(a) cis-3-hexene
(b) cis-1-chloro-2-bromoethene
(c) 2 -pentyne
(d) trans-6-ethyl-7-methyl-2-octene

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Problem 23

Benzene is one of the compounds used as an octane enhancer in unleaded gasoline. It is manufactured by the catalytic conversion of acetylene to benzene:
$3 \mathrm{C}_{2} \mathrm{H}_{2} \longrightarrow \mathrm{C}_{6} \mathrm{H}_{6}$
Draw Lewis structures for these compounds, with resonance structures as appropriate, and determine the hybridization of the carbon atoms in each.

Aadit S.

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Problem 24

Teflon is prepared by the polymerization of tetrafluoroethylene. Write the equation that describes the polymerization using Lewis symbols.

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Problem 25

Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.
(a) $1 \mathrm{~mol}$ of 1 -butyne reacts with $2 \mathrm{~mol}$ of iodine.
(b) Pentane is burned in air.

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Problem 26

Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.
(a) 2 -butene reacts with chlorine.
(b) benzene burns in air.

Aadit S.

Numerade Educator

Problem 27

What mass of 2-bromopropane could be prepared from $25.5 \mathrm{~g}$ of propene? Assume a $100 \%$ yield of product.

Gul R.

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Problem 28

Acetylene is a very weak acid; however, it will react with moist silver(I) oxide and form water and a compound composed of silver and carbon. Addition of a solution of HCl to a 0.2352 -g sample of the compound of silver and carbon produced acetylene and $0.2822 \mathrm{~g}$ of $\mathrm{AgCl}$.
(a) What is the empirical formula of the compound of silver and carbon?
(b) The production of acetylene on addition of HCl to the compound of silver and carbon suggests that the carbon is present as the acetylide ion, $\mathrm{C}_{2}{ }^{2-} .$ Write the formula of the compound showing the acetylide ion.

Aadit S.

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Problem 29

Ethylene can be produced by the pyrolysis of ethane:
$\mathrm{C}_{2} \mathrm{H}_{6} \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4}+\mathrm{H}_{2}$
How many kilograms of ethylene is produced by the pyrolysis of $1.000 \times 10^{3} \mathrm{~kg}$ of ethane, assuming a $100.0 \%$ yield?

Gul R.

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Problem 30

Why do the compounds hexane, hexanol, and hexene have such similar names?

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Problem 31

Write condensed formulas and provide IUPAC names for the following compounds:
(a) ethyl alcohol (in beverages)
(b) methyl alcohol (used as a solvent, for example, in shellac)
(c) ethylene glycol (antifreeze)
(d) isopropyl alcohol (used in rubbing alcohol)
(e) glycerine

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Problem 32

Give the complete IUPAC name for each of the following compounds:
(a)
(b)
(c)

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Problem 33

Give the complete IUPAC name and the common name for each of the following compounds:
(a)
(b)
(c)

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Problem 34

Write the condensed structures of both isomers with the formula $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$. Label the functional group of each isomer.

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Problem 35

Write the condensed structures of all isomers with the formula $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}$. Label the functional group (or groups) of each isomer.

Nicholas S.

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Problem 36

Draw the condensed formulas for each of the following compounds:
(a) dipropyl ether
(b) 2,2 -dimethyl-3-hexanol
(c) 2 -ethoxybutane

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Problem 37

MTBE, Methyl tert-butyl ether, $\mathrm{CH}_{3} \mathrm{OC}\left(\mathrm{CH}_{3}\right)_{3}$, is used as an oxygen source in oxygenated gasolines. MTBE is manufactured by reacting 2 -methylpropene with methanol.
(a) Using Lewis structures, write the chemical equation representing the reaction.
(b) What volume of methanol, density $0.7915 \mathrm{~g} / \mathrm{mL},$ is required to produce exactly $1000 \mathrm{~kg}$ of MTBE, assuming a $100 \%$ yield?

Gul R.

Numerade Educator

Problem 38

Write two complete balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.
(a) propanol is converted to dipropyl ether
(b) propene is treated with water in dilute acid.

Aadit S.

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Problem 39

Write two complete balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.
(a) 2 -butene is treated with water in dilute acid
(b) ethanol is dehydrated to yield ethene

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Problem 40

Order the following molecules from least to most oxidized, based on the marked carbon atom:

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Problem 41

Predict the products of oxidizing the molecules shown in this problem. In each case, identify the product that will result from the minimal increase in oxidation state for the highlighted carbon atom:
(a)
(b)
(c)

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Problem 42

Predict the products of reducing the following molecules. In each case, identify the product that will result from the minimal decrease in oxidation state for the highlighted carbon atom:
(a)
(b)
(c)

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Problem 43

Explain why it is not possible to prepare a ketone that contains only two carbon atoms.

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Problem 44

How does hybridization of the substituted carbon atom change when an alcohol is converted into an aldehyde? An aldehyde to a carboxylic acid?

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Problem 45

Fatty acids are carboxylic acids that have long hydrocarbon chains attached to a carboxylate group. How does a saturated fatty acid differ from an unsaturated fatty acid? How are they similar?

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Problem 46

Write a condensed structural formula, such as $\mathrm{CH}_{3} \mathrm{CH}_{3}$, and describe the molecular geometry at each carbon atom.
(a) propene
(b) 1 -butanol
(c) ethyl propyl ether
(d) $c$ is -4 -bromo- 2 -heptene
(e) 2,2,3 -trimethylhexane
(f) formaldehyde

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Problem 47

Write a condensed structural formula, such as $\mathrm{CH}_{3} \mathrm{CH}_{3}$, and describe the molecular geometry at each carbon atom.
(a) 2 -propanol
(b) acetone
(c) dimethyl ether
(d) acetic acid
(e) 3 -methyl-1-hexene

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Problem 48

The foul odor of rancid butter is caused by butyric acid, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}$.
(a) Draw the Lewis structure and determine the oxidation number and hybridization for each carbon atom in the molecule.
(b) The esters formed from butyric acid are pleasant-smelling compounds found in fruits and used in perfumes. Draw the Lewis structure for the ester formed from the reaction of butyric acid with 2 -propanol.

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Problem 49

Write the two-resonance structures for the acetate ion.

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Problem 50

Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures:
(a) ethanol reacts with propionic acid
(b) benzoic acid, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CO}_{2} \mathrm{H},$ is added to a solution of sodium hydroxide

Aadit S.

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Problem 51

Write two complete balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.
(a) 1 -butanol reacts with acetic acid
(b) propionic acid is poured onto solid calcium carbonate

Aadit S.

Numerade Educator

Problem 52

Yields in organic reactions are sometimes low. What is the percent yield of a process that produces $13.0 \mathrm{~g}$ of ethyl acetate from $10.0 \mathrm{~g}$ of $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H} ?$

Aadit S.

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Problem 53

Alcohols $A, B,$ and $C$ all have the composition $C_{4} H_{10}$ O. Molecules of alcohol A contain a branched carbon chain and can be oxidized to an aldehyde; molecules of alcohol B contain a linear carbon chain and can be oxidized to a ketone; and molecules of alcohol C can be oxidized to neither an aldehyde nor a ketone. Write the Lewis structures of these molecules.

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Problem 54

Write the Lewis structures of both isomers with the formula $\mathrm{C}_{2} \mathrm{H}_{7} \mathrm{~N}$.

Nicholas S.

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Problem 55

What is the molecular structure about the nitrogen atom in trimethyl amine and in the trimethyl ammonium ion, $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{NH}^{+} ?$ What is the hybridization of the nitrogen atom in trimethyl amine and in the trimethyl ammonium ion?

Aadit S.

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Problem 56

Write the two resonance structures for the pyridinium ion, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}$.

Queenie S.

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Problem 57

Draw Lewis structures for pyridine and its conjugate acid, the pyridinium ion, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}$. What are the geometries and hybridizations about the nitrogen atoms in pyridine and in the pyridinium ion?

Aadit S.

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Problem 58

Write the Lewis structures of all isomers with the formula $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{ON}$ that contain an amide linkage.

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Problem 59

Write two complete balanced equations for the following reaction, one using condensed formulas and one using Lewis structures.
Methyl amine is added to a solution of HCl.

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Problem 60

Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.
Ethylammonium chloride is added to a solution of sodium hydroxide.

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Problem 61

Identify any carbon atoms that change hybridization and the change in hybridization during the reactions in Exercise 20.26

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Problem 62

Identify any carbon atoms that change hybridization and the change in hybridization during the reactions in Exercise $20.39 .$

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Problem 63

Identify any carbon atoms that change hybridization and the change in hybridization during the reactions in Exercise 20.51.

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